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cusps by reduction, and this may be the case — as is shortly to 
be shown — with the carnassial itself of the Carnivora. The 
whole foundation of Tims theorv is a mistake and consequeutl\ 
the theory itself is a failure also. 
Fleischmann’s hypothesis that upper and lower teeth are 
homologous in reversed position, is a very peculiar one. According 
to Owen’s definition (in “Lectures on the Comp. Anat. a. Physiol. 
of the Invertebrate Anim., delivered at the Roy. Coll. of Surg. 
1843”) the term “homologous” is used for “the same organ in 
different animals under every variety of form and function.” There 
are different kinds of homology. The fore and hind limbs — or 
the different vertebræ of the backbone — are serially homologous, 
although they are developed in different directions. The limbs of 
the right and the left side are symmetrically homologous (“homotypy”). 
The fore limbs of e. g. man, whale and bird are also homologous 
(“incomplete homology”), being functional differentiations of organs 
of si milar origin. On the other hånd the wings of birds and insects 
are merely analogous: organs of different origin, but of the same 
function. — The upper teeth are serially homologous. If it can 
be demonstrated that they have the same origin, then the anterior 
and posterior portion of one tooth is correspondingly homologous 
with that of the other. The same is the case with the various 
parts of the lower teeth. The upper and lower teeth are no doubt 
homologous qua teeth, but of their single parts only those cusps 
may be called homologous which one can demonstrate to be iden- 
tical with the reptilian cone itself. All the remaining cusps are 
analogous parts, formed by reciprocal action between the opposing 
teeth in the two jaws. When Fleischmann asserts that the anterior 
portion of the upper molar is homologous with the posterior portion 
of the lower molar etc., it is sure ly a misunderstanding of the 
term “homologous”. If such were the case, it necessitates the 
original position of the lower teeth in the upper jaw and a subse- 
quent removal and a reversed position in the lower jaw — which 
is absurd. — A careful comparison of the various mammalian 
